Following the lines of Theorem 6.3.2 of [1]}, we extend the Wiener process \(W\)  for negative \(t\)  by
\(\overline{W}(t) ={\left\lbrace \begin{array}{ll}W(t), \text{ for } t \ge 0,\\V(-t), \text{ if } t \le 0,\end{array}\right.}\) 
